JP5242994B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention relates to a solid oxide fuel cell stack in which a plurality of solid oxide fuel cells each including a solid electrolyte body (solid oxide) having a fuel electrode and an air electrode are stacked, and the solid oxide fuel cell stack The present invention relates to a solid oxide fuel cell including an output conductive member that extracts an output from the fuel cell.

Conventionally, a solid oxide fuel cell (hereinafter also referred to as SOFC) including a solid electrolyte (solid oxide) used at a high temperature is known as a fuel cell.
In this SOFC, as a power generation unit, for example, a power generation cell in which a fuel electrode in contact with fuel gas is provided on one side of a layered solid electrolyte body and an air electrode in contact with air is provided on the other side is used. In order to improve performance, SOFCs in which a plurality of the cells are stacked have been developed.

  Among these, as described in Patent Document 1 below, a stack structure of SOFC is known in which the entire stack is fastened by a holding plate (end plate). In this method, the entire stack is tightened with an end plate, so that the pressure applied to the seal portion between the cells and the contact of the current collector with the electrode in each cell are simultaneously performed.

In addition, the electrical output generated in the entire stack is generally taken out from the end plate, and a fixing member such as a bolt can be used as a member for fastening the entire stack. It has been studied to use a member for taking out the output from the stack and to connect a lead (lead wire) to the member for taking out the output.
JP 2005-183089 A

  Since the above-described SOFC is operated at a high temperature, the output lead-out conductor is also very hot. However, when the connecting portion between the fixing member and the conducting wire becomes high temperature, depending on the material, the conducting wire is oxidized, or the contact resistance at the connecting portion increases due to the thermal expansion difference between the fixing member and the conducting wire, resulting in a decrease in output. was there.

  As a countermeasure, for example, it is conceivable to integrate the end plate and the conductive wire. However, in that case, the component size becomes large, which causes a problem in handling. In addition, it is conceivable to weld a conductive wire to the terminal portion of the stack, but this is not preferable because there is a problem that the stack locally becomes hot and the terminal portion is deformed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a solid oxide fuel cell that can suitably reduce the contact resistance between a stack and an output extraction member. .

(1) The invention of claim 1 is a solid electrolyte body, a fuel electrode provided on one surface of the solid electrolyte body and in contact with the fuel gas, and an air provided on the other surface of the solid electrolyte body and in contact with the oxidant gas. A solid oxide fuel cell stack in which a plurality of solid oxide fuel cells having a plurality of electrodes are stacked, and the solid oxide fuel cell stack includes a stack-side output terminal portion that is an output terminal thereof. In the solid oxide fuel cell, an output conductive member for extracting an output from the solid oxide fuel cell stack to the outside is connected to the stack side output terminal portion, and the stack side output terminal portion and the output the connecting portion between Yoshirubeden member, conductive intermediate material made of silver or an alloy containing silver is interposed, and the conductive intermediate material, with a foil made of silver or an alloy containing silver, before The alloy containing silver contains at least one of palladium, copper, and titanium, and further, the stack side output terminal portion and the output conductive member are screwed via the conductive intermediate material. The connection portion of the stack side output terminal portion is a female screw, the connection portion of the output conductive member is a male screw, and is in close contact with both surfaces of the male screw and the female screw. As described above, the conductive intermediate material is arranged .

In the present invention, since the conductive intermediate material mainly composed of silver or an alloy containing silver is interposed in the connection portion between the stack side output terminal portion and the output conductive member, the electrical contact resistance can be reduced. it can. This solves the problems of conventional technologies (for example, enlargement of parts when the end plate is integrated with the conductive material, deterioration of the stack when welding the conductive wires, etc.) and suppresses a decrease in the output of the fuel cell. There is a remarkable effect of being able to.
Further, in the present invention, the conductive intermediate material is a foil made of silver or an alloy containing silver, and according to the experiments by the present inventors, the work using the foil as the conductive intermediate material is easy. In addition, the contact resistance is small and suitable.
Furthermore, in this invention, the alloy containing silver contains at least 1 sort (s) among palladium, copper, and titanium.
In addition, according to the present invention, the stack side output terminal portion and the output conductive member are coupled by screwing through the conductive intermediate material, thereby simplifying the configuration and manufacturing method of the fuel cell. Can do.
In addition, in the present invention, since the connection portion of the stack side output terminal portion is a female screw and the connection portion of the output conductive member is a male screw, the configuration on the stack side can be simplified, and the connection work is easy.
Furthermore, in this invention, the electroconductive intermediate material is arrange | positioned so that it may contact | adhere to both surfaces of a male screw and a female screw. For example, a large output can be taken out with a compact configuration without causing adverse effects due to heat when the lead portions are welded.

Here, a stack-side output terminal portion and the output conductive member and is connected, both members having conductivity, through a conductive intermediate member, Ru mechanically connected to the screwing between the male screw and the female screw This means that it is electrically connected.

  Moreover, as an alloy containing silver, the alloy (silver 50 mass% or more) which has silver as a main component is preferable, and since the electrical contact resistance becomes small, the higher the silver content rate, it is suitable. Examples of the alloy containing silver include Ag—Pd, Ag—Al, Ag—Cu, and Ag—Ni.

( 2 ) The invention of claim 2 is characterized in that the output conductive member is made of a material mainly composed of nickel.
In the present invention, since the output conductive member is made of a material mainly composed of nickel, it is excellent in heat resistance and conductivity.

Here, having nickel as a main component indicates that the nickel content is 50% by mass or more.
Here, the solid electrolyte body (solid oxide body) moves, as ions, one part of the fuel gas introduced into the fuel electrode or the oxidant gas introduced into the air electrode during the operation of the battery. Have ionic conductivity. Examples of the ions include oxygen ions and hydrogen ions. Further, the fuel electrode comes into contact with the fuel gas that becomes the reducing agent and functions as a negative electrode in the cell. The air electrode is in contact with an oxidant gas serving as an oxidant and functions as a positive electrode in the cell.

Examples of the material of the solid electrolyte body (solid oxide body) include ZrO ₂ ceramics, LaGaO ₃ ceramics, BaCeO ₃ ceramics, SrCeO ₃ ceramics, SrZrO ₃ ceramics, and CaZrO ₃ ceramics.

As the material of the fuel electrode, for example, ZrO ₂ ceramics such as zirconia stabilized by at least one of metals such as Ni and Fe and rare earth elements such as Sc and Y, CeO ₂ ceramics, etc. The mixture with at least 1 sort (s) of ceramics etc. are mentioned. Moreover, metals, such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, are mentioned. These metals may be used alone or in an alloy of two or more metals. Further, a mixture (including cermet) of these metals and / or alloys and at least one of each of the above ceramics may be mentioned. Moreover, the mixture of metal oxides, such as Ni and Fe, and at least 1 type of each of the said ceramic etc. are mentioned.

As the material for the air electrode, for example, various metals, metal oxides, metal double oxides, and the like can be used. Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh, or alloys containing two or more metals. Furthermore, examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn and Fe (La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO ₂ and FeO). It is done. As the double oxide, a double oxide containing at least La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (La _1-x Sr _x CoO ₃ -based double oxide, La _1-x Sr _x FeO ₃ -based double oxide, La _1-x Sr _x Co _1-y Fe _y O ₃ -based double oxide, La _1-x Sr _x MnO ₃ -based double oxide, Pr _1-x Ba _x CoO ₃ -based double oxide Oxide and Sm _1-x Sr _x CoO ₃ -based double oxide).

-When generating power using a solid oxide fuel cell, a fuel gas is introduced to the fuel electrode side and an oxidant gas is introduced to the air electrode side.
Examples of the fuel gas include hydrogen, hydrocarbons, a mixed gas of hydrogen and hydrocarbons, a fuel gas obtained by passing these gases through water at a predetermined temperature and humidified, and a fuel gas obtained by mixing these gases with water vapor. It is done. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. The fuel gas is preferably hydrogen. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.

  Examples of the oxidizing gas include a mixed gas of oxygen and another gas. Further, the mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Of these oxidant gases, air (containing about 80% by volume of nitrogen) is preferred because it is safe and inexpensive.

Next, an example of the best mode of the present invention, that is, an example of a solid oxide fuel cell will be described. Examples 2 and 3 are reference examples.

a) First, the configuration of a solid oxide fuel cell module (hereinafter simply referred to as a fuel cell) will be described.
As shown in FIGS. 1 and 2, the fuel cell 1 according to the present embodiment generates power by receiving supply of a fuel gas (for example, hydrogen) and an oxidant gas (for example, air (specifically, oxygen in the air)). A solid oxide fuel cell stack (hereinafter simply referred to as fuel) in which a plurality (for example, 15) of plate-like solid oxide fuel cells (hereinafter simply referred to as fuel cells) 3 as a power generation unit are stacked. 5) (referred to as a battery stack).

  Stack side output terminal portions (holding plates: end plates) 7 and 9 that press the plurality of fuel cells 3 and are used as output terminals of the fuel cell stack 5 are disposed on both sides of the fuel cell stack 5 in the stacking direction. The fuel cell stack 5 is clamped and fixed by first to eighth fixing members 11 to 25 passing through the fuel cell stack 5 in the stacking direction via the end plates 7 and 9 and integrated. ing.

  Further, as shown in FIG. 3A, the fuel gas side channel of the cell and the air side channel shown in FIG. 3B, the fuel cell 3 is a so-called fuel electrode support membrane type cell. A fuel electrode (anode: negative electrode) 29 is disposed on the fuel gas flow path 27 side, and a thin solid electrolyte body 31 is formed on the upper surface of the fuel electrode 29. An air electrode (cathode: positive electrode) 35 is formed on the surface on the air flow path 33 side. Here, the fuel electrode 29, the solid electrolyte body 31, and the air electrode 35 are referred to as a cell body 37.

  Conductive metal connector plates 39 are arranged on both sides of the fuel cell 3 in the thickness direction (vertical direction in FIG. 3), and the fuel cell 3 is divided (gas flow) by the connector plate 39. In addition, the continuity in the thickness direction is ensured.

  Here, the connector plate 69 sandwiched between the adjacent fuel cells 3 is an interconnector, and the connector plates 39 at the upper and lower ends of the fuel cell stack 5 are the end plates 7 and 9. In this embodiment, the first end plate 7 at the upper end serves as a positive electrode, and the second end plate 9 at the lower end serves as a negative electrode.

Further, a current collector 41 is disposed between the air electrode 35 and the upper connector plate 39 in order to ensure the electrical connection.
Further, the fuel cell 3 includes a metal air electrode frame 43 on the air flow path 33 side, a ceramic insulating frame 45, and a cell body 37 so as to surround the cell body 37 and the current collector 41. And a metallic separator 47 for blocking the gas flow path, and a metallic fuel electrode frame 49 on the fuel gas flow path 27 side.

  The frame portion of the fuel cell 3 through which the first to eighth fixing members 11 to 25 penetrate by the air electrode frame 43, the insulating frame 45, the separator 47, the fuel electrode frame 49, and the connector plate (outer peripheral edge portion) 39 thereof. 51 is configured.

  Further, as shown in FIG. 1, the first to eighth fixing members 11 to 25 are arranged so as to penetrate through holes 53 to 67 formed in the frame portion 51 of the fuel cell stack 5. 5 is a member that presses 5 in the stacking direction and is integrally fixed, and includes bolts 11a to 25a (through the through holes 53 to 67) and nuts 11b to 25b that are screwed to the bolts 11a to 25a, respectively.

  Among these, the bolts 13a, 17a, 21a, and 25a of the second, fourth, sixth, and eighth fixing members 13, 17, 21, and 25 are hollow bolts having gas passages therein, The bolt 21a of the fixing member 21 is used as a flow path for supplying fuel gas, and the bolt 13a of the second fixing member 13 is used as a flow path for discharging fuel gas. Further, the bolt 25a of the eighth fixing member 25 is used as a flow path for supplying air, and the bolt 17a of the fourth fixing member 17 is used as a flow path for discharging air. The first, third, fifth, and seventh fixing members 11, 15, 19, and 23 are solid bolts and are used to fix the fuel cell stack 5.

  4, for example, the bolt 19a of the fifth fixing member 19 is inserted into the through hole 61 of the fuel cell stack 5, and the lower side is as shown in FIG. It is fixed by a lower nut 19c, and its upper side is fixed by an upper nut 19b.

  Further, between the upper and lower nuts 19 b and 19 c and the end plates 7 and 9, for example, a plate shape made of mica ceramic so that the fifth fixing member 19 and the end plates 7 and 9 are not short-circuited. Insulators 69 and 71 are arranged.

  Further, cylindrical insulating spacers 73 and 75 made of, for example, mica ceramic are fitted into both upper and lower ends of the through hole 61, and the bolt 19 a passes through the through holes 74 and 76 of the insulating spacers 73 and 75. It is inserted. That is, the insulating spacers 73 and 75 are arranged in the through hole 61 so that the bolt 19 a does not contact the inner peripheral surface of the through hole 61.

  Note that the configuration in which the fifth fixing member 19 is assembled with the fuel cell stack 5 while maintaining the insulating properties using the insulating spacers 73 and 75 is the same for the other fixing members, and thus the description thereof is omitted.

  In this embodiment, the end plates 7 and 9 are, for example, stainless steel plates having excellent heat resistance and conductivity, and the end plates 7 and 9 are leads for taking out power from the stack, respectively. As part, rod-shaped output conductive members 77 and 79 made of, for example, nickel excellent in heat resistance and conductivity are connected and fixed.

  That is, as shown in an enlarged view in FIG. 5, for example, a screw hole 81 for a female screw is formed on the side surface of the upper end plate (first end plate) 7, and connected to the first end plate 7. A screw portion 83 of a male screw is formed on the outer periphery of the output conductive member (first output conductive member) 77, and the first end plate 7 and the first output screw are engaged by screwing the male screw and the female screw. A conductive member 77 is connected.

  In particular, in this embodiment, a thin conductive intermediate material 85 having high conductivity made of silver (or a silver alloy containing silver as a main component) is disposed inside the screw hole 81. Specifically, a conductive intermediate material 85 made of silver foil is disposed between the male screw and the female screw, which are the side wall portions of the screw hole 81, so as to be in close contact with both surfaces of the male screw and the female screw.

  Further, as described above, since the screw portion 83 is formed on the entire outer periphery of the first output conductive member 77, until the tip portion 87 of the first output conductive member 77 contacts the bottom portion 89 of the screw hole 81. Can be screwed in.

The connecting portion between the lower end plate (second end plate) 9 and the output conductive member (second output conductive member) 79 has the same configuration.
b) Next, the gas flow path of the fuel cell 1 will be described.

(1) Fuel flow path As shown in FIG. 6A (cross-sectional view along YY in FIG. 1), the fuel gas supplied from the fuel inlet 91 above the sixth fixing member 21 of the fuel cell 1 is It is supplied to the fuel gas flow path 27 in each cell 3 through the hollow portion 93 and the horizontal hole 95 of the bolt 21a.

  Next, after the fuel gas in the fuel gas flow path 27 in each cell 3 flows along the fuel electrode 29, the fuel gas flows through the similar lateral hole 97 and the hollow portion 99 of the bolt 13 a of the second fixing member 13. The fuel is discharged from the outlet 101 to the outside of the fuel cell 1.

(2) Air flow path As shown in FIG. 6B (XX cross-sectional view in FIG. 1), the air supplied from the air inlet 103 above the eighth fixing member 25 of the fuel cell 1 is a bolt. The air is supplied to the air flow path 33 in each cell 3 through the hollow portion 105 and the lateral hole 107 of 25a.

  Next, after the air in the air flow path 33 in each cell 3 flows along the air electrode 35, the air outlet 113 passes through the similar lateral hole 109 and the hollow portion 111 of the bolt 17 a of the fourth fixing member 17. To the outside of the fuel cell 1.

c) Next, a method for manufacturing the fuel cell 1 will be briefly described.
First, a plate material made of, for example, SUS430 (as a member constituting the fuel cell stack 5) was punched out (excluding the end plates 7 and 9) to produce a connector plate 39, an air electrode frame 43, a separator 47, and a fuel electrode frame 49. .

  Of the connector plate 39, the end plates 7 and 9 are thick, and thus formed by machining to cut a plate material. And the screw hole 81 was formed in the side surface of each end plate 7 and 9, respectively.

In addition, an insulating frame 45 was manufactured by forming a green sheet mainly composed of a mixture of MgO and spinel into a predetermined shape and firing it by a conventional method.
The cell body 37 of the fuel cell 3 was manufactured according to a conventional method. Specifically, the material of the solid electrolyte body 31 was printed on the green sheet of the fuel electrode 29, the material of the air electrode 35 was printed thereon, and then fired. The cell body 37 was fixed to the separator 47 by brazing.

  Next, the connector plate 39, the air electrode frame 43, the insulating frame 45, the separator 47 (with the cell main body 37 brazed), the fuel electrode frame 49, the current collector 41, etc. are assembled together to assemble each fuel cell 3. At the same time, each fuel battery cell 3 was stacked to form a fuel battery stack 5. Of the connector plate 39, the thick end plates 7 and 9 are arranged on both sides in the stacking direction of the stacked body.

  Next, the bolts 11a to 25a are fitted into the through holes 53 to 67 of the fuel cell stack 5 via the insulating spacers 73 and 75 and the insulators 69 and 71, and nuts 11b to 25b and 19c are attached to both ends thereof. Screwed together. The insulating spacers 73 and 75 were fitted into the through holes 53 to 67, and the insulators 69 and 71 were disposed on the stack surface.

Thereafter, the nuts 11b to 25b and 19c were tightened, and the fuel cell stack 5 was pressed and integrated and fixed.
Next, using nickel-made output conductive members 77 and 79 which are screw members manufactured separately, silver foil was wound around the outer periphery of the screw portion 83 at the tip as a conductive intermediate material 85. Then, in this state, the screw portion 83 is screwed into the screw holes 81 of the end plates 9 and 8 to fix the fuel cell 1.

  c) Thus, in the fuel cell 1 of the present embodiment, a thin film having high conductivity made of silver so as to be in close contact with both surfaces of the external threads of the output conductive members 77 and 79 and the internal threads of the end plates 7 and 9. Therefore, the electrical contact resistance can be greatly reduced. Therefore, there is a remarkable effect that a large output can be taken out with a compact configuration without causing problems such as an adverse effect due to heat when the lead portion is welded.

  Further, since the bolts 11a to 25a of the respective solid members 11 to 25 are held at predetermined intervals from the inner peripheral surfaces of the respective through holes 53 to 67 by the insulating spacers 73 and 75, the solid members 11 to 25 and A short circuit with the fuel cell stack 5 can be prevented.

  As the conductive intermediate material 85, a silver alloy foil or the like can be used instead of the silver foil. Alternatively, the screw portion 83 may be screwed into the screw hole 81 after a paste such as silver is applied to the outer periphery of the screw portion 83 of the output conductive members 77 and 79 and then dried. In this case, the dried silver material becomes a conductive intermediate material made of silver or a silver alloy due to a high temperature during operation.

Next, the second embodiment will be described, but the description of the same contents as the first embodiment will be omitted.
In this embodiment, a fixing member such as a nut is used as the output conductive member.
As shown in FIG. 7, in the fuel cell 121 of the present embodiment, the fuel cell stack 129 is fixed integrally by the first and second fixing members 123 and 125 (other fixing members are not shown). Has been.

  Specifically, the first and second fixing members 123 and 125 are each composed of bolts 131 and 133 and nuts 135, 137, 139, and 141, and each bolt 131 and 133 is opened in the stacking direction of the fuel cell stack 129. The fuel cell stack 129 is fastened by being inserted into the through holes 143 and 145 and nuts 135 to 141 screwed to both sides of the bolts 131 and 133.

  Further, the bolts 131 and 133 of the first and second fixing members 123 and 125 are respectively connected to the through holes by cylindrical spacers 147, 149, 151 and 153 fitted into the upper and lower ends of the through holes 143 and 145. Predetermined intervals are maintained so as not to contact the inner peripheral surfaces of 143 and 145.

  In particular, in this embodiment, an insulator 157 is disposed between the upper nut 135 and the upper end plate 155 of the first fixing member 123, but the lower nut 137 and the lower end plate 159 A conductive intermediate material 161 made of a silver foil having high conductivity is disposed between them.

  Accordingly, since only conduction between the lower end plate 159, the lower nut 137, and the bolt 131 is ensured, the first fixing member 123 is connected to the lower end plate 159, for example, the lead portion on the negative electrode side. Can be used as

  On the other hand, an insulator 163 is disposed between the lower nut 141 and the lower end plate 159 of the second fixing member 125, but between the upper nut 139 and the upper end plate 155, A conductive intermediate material 165 made of a silver foil having high conductivity is disposed.

  Therefore, only conduction between the upper end plate 155, the upper nut 139, and the bolt 133 is ensured, so that the second fixing member 125 is used as, for example, a positive lead portion of the upper end plate 155. Can do.

  As described above, in this embodiment, the conductive intermediate members 161 and 165 are arranged between the nuts 137 and 139 and the end plates 155 and 159 of the fixing members 123 and 125, and the bolts 131 of the fixing members 125 and 125 are arranged. Since 133 can be used as the output conductive member, there is an advantage that it is not necessary to provide a separate screw hole or the like and the configuration can be further simplified.

Next, the third embodiment will be described, but the description of the same contents as the second embodiment will be omitted.
In this embodiment, the end plate is extended, and a plate-like output conductive member is fixed to the extended portion with a bolt.

  As shown in FIG. 8, in the fuel cell 171 of this embodiment, the fuel cell stack 177 is integrally fixed by the first and second fixing members 173 and 175 (other fixing members are not shown). Has been.

  Specifically, the first and second fixing members 173 and 175 include bolts 181 and 183 and nuts 185, 187, 189 and 191, respectively. The nuts 185 to 191 are screwed on both sides of the bolts 181 and 183.

  In addition, the bolts 181 and 183 of the first and second fixing members 173 and 175 are inserted into the through holes 193 and 195 by insulating spacers 197, 199, 201 and 203 fitted in the through holes 193 and 195. A predetermined interval is maintained so as not to contact the peripheral surface.

  Further, an insulator 207 is disposed between the upper nut 185 and the upper end plate 205 of the first fixing member 173 to ensure insulation, but the lower nut 187 and the lower end plate are secured. 209 is in direct contact.

  On the other hand, the insulator 211 is disposed between the nut 191 below the second fixing member 175 and the lower end plate 209 to ensure insulation, but the upper nut 189 and the upper end plate are secured. 205 is in direct contact to ensure conductivity.

  Thereby, both end plates 205 and 209 are configured not to be short-circuited by the fixing members 173 and 175. The nuts 187 and 189 are not used for conduction, and may be fixed via insulating plates.

  In particular, in this embodiment, one end side (the right side of the figure) of both end plates 205 and 209 used as the stack side output terminal extends outward so as to protrude from the fuel cell stack 177.

  An output conductive member 217 made of plate-like nickel is laminated on the surface of the extended portion 213 of the upper end plate 205 via a conductive intermediate material 215 made of silver foil. The conductive member 217 is coupled by being tightened by a bolt 221 inserted through a through hole 219 that passes through the conductive member 217 and a nut 223 screwed into the bolt 221.

  Similarly, on the surface of the extended portion 225 of the lower end plate 209, a similar output conductive member 229 is laminated via a conductive intermediate material 227 made of silver foil, and these are inserted into the through holes 231. The bolts 233 and nuts 235 are tightened and connected.

Also in this embodiment, the same effects as in the second embodiment are obtained.
(Experimental example)
Next, Experimental Examples 1 to 3 performed for confirming the effects of the present invention will be described.

a) Experimental Example 1
In this experimental example, as shown in Table 1 below, fuel cells having the same configuration as in Example 1 or Example 3 were manufactured as Samples 1 to 7 within the scope of the present invention used in the experiment. Further, as a comparative example outside the scope of the present invention, a fuel cell of Sample 8 was manufactured. Here, the material of the end plate is SUS430, and the material of the output conductive member is nickel.

  Each sample fuel cell was operated at 800 ° C. for 1000 hours to perform a durability test, and the change in resistance value between the pair of output conductive members was examined before and after the durability test. The results (increase in resistance after endurance) are shown in Table 2 below.

この表２から明かな様に、本発明の範囲の試料１〜７は、耐久後の抵抗値の増加が少なく好適であるが、比較例の試料８は、抵抗値の増加が大きく好ましくない。

As is apparent from Table 2, Samples 1 to 7 within the scope of the present invention are preferable because of little increase in resistance after endurance, but Sample 8 of the comparative example is not preferable because of large increase in resistance.

b) Experimental example 2
In this experimental example, in the same manner as in Experimental Example 1, the fuel cells of Samples 9 to 15 (same configuration as Samples 1 to 7) within the scope of the present invention and the Sample 16 (same as Sample 8) of the comparative example range. Manufactured). However, here, both the end plate and the conductive member for output were made of SUS430 (otherwise, the same as in Experimental Example 1).

  Then, an endurance test was performed in the same manner as in Experimental Example 1, and the change in the resistance value was similarly examined. The results are shown in Table 3 below.

この表３から明かな様に、本発明の範囲の試料９〜１５は、耐久後の抵抗値の増加が少なく好適であるが、比較例の試料１６は、抵抗値の増加が大きく好ましくない。

As is apparent from Table 3, Samples 9 to 15 within the scope of the present invention are preferable because of little increase in resistance value after endurance, but Comparative Example Sample 16 is not preferable because of an increase in resistance value.

Further, as is apparent from Tables 2 and 3, it can be seen that it is preferable to use nickel as the material of the output conductive member since the increase in resistance value is small.
c) Experimental example 3
In Experimental Example 3, the effect of the insulating spacer was examined.

  Specifically, five fuel cells having the structure of Example 2 were manufactured as Sample 17. Specifically, a fuel cell was manufactured in which the diameter of the bolt as a fixing member was φ12 mm, the inner diameter of the through hole of the stack was φ18 mm, the outer diameter of the insulating spacer was φ18 mm, the inner diameter was φ12 mm, and the thickness was 1 mm.

Further, as the sample 18, five fuel cells having the same configuration as that of the sample 17 but excluding only the insulating spacer were manufactured.
Then, after performing an endurance test in the same manner as in Experimental Example 1, the occurrence of an electrical short was examined.

As a result, the short-circuit occurrence rate was 0/5 when the insulating spacer was used, but the short-circuit occurrence rate was 2/5 when the insulating spacer was not used.
Needless to say, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the present invention.

1 is a perspective view showing a solid oxide fuel cell module of Example 1. FIG. 1 is a front view showing a solid oxide fuel cell module of Example 1. FIG. (A) Explanatory drawing which decomposes | disassembles and shows the fuel flow path side of a solid oxide fuel cell, (b) Explanatory drawing which decomposes | disassembles and shows the air flow path side of a solid oxide fuel cell. It is AA sectional drawing of FIG. It is explanatory drawing which expands and shows a partially broken main part of the solid oxide fuel cell module. (A) Explanatory drawing which shows the YY cross section of FIG. 1, (b) Explanatory drawing which shows the XX cross section of FIG. It is explanatory drawing which fractures | ruptures and shows the principal part of the solid oxide fuel cell module of Example 2. FIG. It is explanatory drawing which fractures | ruptures and shows the principal part of the solid oxide fuel cell module of Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 121, 171 ... Solid oxide fuel cell module 3 ... Solid oxide fuel cell 5, 129, 177 ... Solid oxide fuel cell stack 7, 9, 155, 159, 205, 209 ... End plate 29 ... Fuel electrode 31 ... Solid electrolyte body 35 ... Air electrode 73, 75, 147, 149, 151, 153, 197, 199, 201, 203 ... Insulating spacer 77, 79, 123, 125, 217, 229 ... Output conductive Member 85, 161, 165, 215, 227 ... conductive intermediate material

Claims (2)

A solid oxide fuel having a solid electrolyte body, a fuel electrode provided on one surface of the solid electrolyte body and in contact with a fuel gas, and an air electrode provided on the other surface of the solid electrolyte body and in contact with an oxidant gas In addition to a solid oxide fuel cell stack in which a plurality of battery cells are stacked,
In the solid oxide fuel cell stack, the solid oxide fuel cell provided with a stack side output terminal portion that is an output terminal of the stack,
An output conductive member for extracting output from the solid oxide fuel cell stack to the outside is connected to the stack side output terminal portion, and
In the connection portion between the stack side output terminal portion and the output conductive member, a conductive intermediate material made of silver or an alloy containing silver is interposed ,
And the conductive intermediate material is a foil made of silver or an alloy containing silver, and the alloy containing silver contains at least one of palladium, copper, and titanium,
Further, the stack side output terminal portion and the output conductive member are coupled by screwing through the conductive intermediate material,
The connection portion of the stack side output terminal portion is a female screw, the connection portion of the conductive member for output is a male screw, and the conductive intermediate material is disposed so as to be in close contact with both surfaces of the male screw and the female screw. A solid oxide fuel cell. 2. The solid oxide fuel cell according to claim 1, wherein the output conductive member is made of a material mainly composed of nickel.

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